Method of forming slots, splines and the like



Feb. 14, 19.39. E. G. BOYER ,1

METHOD OF FQRMING SLOTS, SPLINES, AND THE LIKE Original Filed Feb. 28, 1935 .ZZzrZe G: .Bqyew Patented Feb. 14, 1939 UNITED STATES METHOD OF FORMING SLOTS, SPLINES AND THE LIKE Earle G. Boyer, Philadelphia, Pa., assignor to Hannifin Manufacturing 00., Chicago, 111., a

corporation of Illinois Original application February 28, 1935, Serial N 0. 8,705, now Patent No. 2,070,780, dated February 16, 1937.

Divided and this application July 30, 1936, Serial No. 93,460

2 Claims.

This invention relates to forming slots, elongated perforations, and splines (particularly. those having outwardly tapered contours) in pipes, tubes and the like, and among other objects, aims to provide an improved type of slot or spline efliciently and at low cost.

The nature of the invention may be readily understood by reference to one embodiment thereof illustrated in the accompanying drawing.

In said drawing:

Fig. l is a longitudinal section through a pipe illustrating the formation of longitudinally extending, outwardly tapering slots;

Fig. 2 is a transverse section taken on the plane 2--2 of Fig. 1, illustrating the manner of simultaneously forming a plurality of such slots;

Fig. 3 is a partial section of the device for controlling the outward travel of the cutting tools; and

Fig. 4 is a detail section taken on the plane 4-4 of Fig, 3.

To simplify the following description, the expression slot will be employed to include the various types of grooves, perforations or splines embraced within the invention, and the expression pipe will be employed to include tubing and other articles adapted to be slotted or the like.

The invention is here shown applied to the manufacture of well strainers III. The latter are advantageously provided with elongated slots II which are outwardly tapered so as to be selfcleaning and to prevent clogging. The formation of such outwardly tapered slots has heretofore involved difiiculties either in the cost of formation of the slots or in the development of weal;- nesses in the strainer pipe. In the latter case, the slots are formed by rotary saws of relatively large diameter (similar to milling cutters) having outwardly tapered contours which result in the formation of excessively elongated internal grooves in the pipe at the ends of the slots. While the slots may be formed rapidly and at moderately low cost by this method, the arrangement of the slots end to end results in the merging of the elongated terminal beveled portions of one slot with that of the next slot, thus forming weakened lines between the slots which frequently crack particularly when the strainer is driven into the well or otherwise subjected to the stresses usually imposed upon well strainers.

According to the present invention, it is possible to form, at no less speed and at no greater cost, slots I I having no elongated grooves or weak spots at their ends but terminating in relatively blunt extremities I2 having the same or not greater taper than the side walls I3 of the slot. The slots are formed by rotating drilling cutters I4 (whose contour is that of the section of the slot or groove to be formed) which penerate the surface from the interior by a drilling action, and are thereupon moved laterally to make an elongated slot.

The tips of the drilling cutters are advantageously in the form of drills capable of drilling a hole, and the conical portions I5 (for forming tapered side walls) are fluted much as a countersinking tool. The cutting edges of both the drilling and the conical portion of the tools are formed to give them milling properties so as to render them capable of milling through the metal by a lateral relative movement, to form a slot. If internal splines or grooves are to be formed, cutters having an appropriately shaped contour are employed.

After penetrating the pipe the proper distance, the cutters are moved relative to the pipe in the direction of the desired slot. This may be either transversely, longitudinally or spirally. Generally the arrangement is either longitudinal, as here shown, or spiral. Slots in longitudinal alignment may be placed relatively closely together without developing any weak spot in the space I6 between the slots, since the ends of the slot have a relatively blunt taper not greater than that of the sides of the slot. Preferably adjacent rows of slots are staggered.

The slots may be formed rapidly and cheaply by simultaneously operating a plurality of cutters I4. For this purpose, the cutters may advantageously be carried in a head I! in this case arranged with six sets of bearings I8 for mounting six radial cutters. Each of the cutters is driven by a sleeve I9 within which it is longitudinally slidable, To transmit rotation, the bit holders 2!] are either splined within the sleeves or, as in the present case, both the holder and the internal bore of the sleeve are made non-circular in section, such for example as hexagonal. The sleeves are each provided with bevel pinions 2I meshing with and driven by a central bevel gear 22 carried on a longitudinally extending spline shaft 23 supported in bearings 24 mounted in a hub projecting from the head I'I. Rotation of the shaft 23 thus rotates all of the cutters simultaneously.

The cutters are moved outwardly to perform the initial drilling operation under the action of a conical wedge 25 having a plurality of grooves 26 within which seat the tapered extremities of the rods 21 which are connected to and extend inwardly from the respective bit holders 20. The conical wedge 25 is rotatively mounted at the end of a feeding screw 28 threaded into the hub 29 on the head. As shown in Figs. 3 and 4, the wedge member is provided with a key or set screw 30 adapted to project into a groove 3| at the end of the screw and thus maintain an operative connection with the screw without interfering with relative rotation. Rotation of the screw causes advance of the conical Wedge relative to the cutters, thus causing a radial movement of the latter. As here shown, the cutters are held in operative connection with the wedge by springs 32 which are mounted between collars 33 seated against shoulders 34 in the sleeves l9 and collars 35 carried by the rods 21. The screw 28 is provided with an operating connection here shown in the form of a transversely extending pin 36 which may be engaged by an appropriate tool to rotate the screw and move the cutters either inwardly or outwardly, as desired.

After the cutters have been driven outwardly, so as to penetrate the pipe by the desired amount (for a groove or spline the pipe will not of course be completely pierced), the head and pipe are moved relatively to form slots. If longitudinal slots be desired, the relative movement is purely longitudinal. If spiral slots be desired, the cutter head and pipe are relatively moved longitudinally and relatively rotated. Upon the completion of a set of slots, the cutters are moved inwardly (by rotating screw 28) to clear the pipe; and thereupon the cutters are moved relative to the pipe to a position where the next set of slots are to be formed.

The cutter head is here shown mounted on a sleeve 31 screwed in the plate 38 on the head. The sleeve serves not only to support the head but in this instance to effect the aforesaid relative movement between the pipe and head to move the same relative to the pipe. The shaft 23 is advantageously provided with a spline 39 to permit the latter to move longitudinally in its driving member.

This application is a division of my application, Serial No. 8,705, filed February 28, 1935, and issuing as Patent No. 2,070,780.

Obviously the invention is not limited to the details of the illustrative construction since these may be variously modified. Moreover, it is not indispensable that all features of the invention be used conjointly since various features may be used to advantage in different combinations and subcombinations.

Having described my invention, I claim:

1. The method of forming in pipes outwardly tapered strainer slots having the same taper at each end as that at the sides of the slot which comprises applying to the interior of the pipe a rotating drilling cutter having a conical contour of the same taper as that desired in said slot, moving the cutter outwardly in a generally radial direction until an outwardly tapered opening is formed in the pipe of a section corresponding to the desired transverse section of the slot, and then while rotating the cutter effecting a relative movement between the cutter and the pipe in the direction of the desired slot to cause the cutter to mill a slot of the aforesaid transverse section.

2. The method of forming in pipes outwardly tapered strainer slots having the same taper at each end as that at the sides of the slot which comprises drilling the pipe from its interior with a rotating drilling cutter having a conical contour of the same taper as that desired in said slot, moving the cutter outwardly until an outwardly tapered opening is formed in the pipe of a section corresponding to the desired transverse section of the slot, and then while rotating the cutter moving the same in the direction of the desired slot to cause the cutter to mill an outwardly tapered slot.

EARLE G. BOYER. 

